LTE is a standard for wireless data communication technology. A goal of LTE is to increase the capacity and speed of wireless data networks. Another goal of LTE is to redesign and simplify the network architecture of an IP-based system with significantly reduced transfer latency compared to the 30G architecture. As shown in FIG. 1, EUTRAN (Evolved Universal Terrestrial Radio Access Network) consists of enhanced NodeBs (eNodeBs) at the network side. eNodeBs are connected to each other via the X2 interface, and they connect to the packet switched core network via the S1 interface.
In the LTE system, cell search means that a User Equipment (UE) acquires downlink synchronization (including time synchronization and frequency synchronization) with a base station and detects a physical-layer ID of a cell. Based on the above information, the UE can receive and read broadcast information of the cell, and acquire system information of the cell so as to determine the subsequent operations, such as cell selection, cell reselection and cell switch. UE can also be referred to as a mobile terminal, mobile phone, mobile communication device etc.
In a LTE system, the cell synchronization may be achieved by a synchronous signal transmitted over a downlink channel. The synchronous signal, which is transmitted in the LTE system every 5 ms, includes a primary synchronous signal (PSS) and a secondary synchronous signal (SSS). For a frequency division duplexing (FDD) mode and a time division duplexing (TDD) mode, the positions of PSS and SSS in a 10 ms frame are shown in FIGS. 2a and 2b respectively.
In the LTE system, the cell search procedure based on PSS and SSS mainly comprises PSS detection and SSS detection. In the prior art, the SSS detection may be performed by using a non-coherent detection method, which generally comprises the steps of:
performing correlation calculation on SSSs from different antennae (if any) and different data blocks (if any) in a frequency domain, to obtain a plurality of SSS correlation sequences;
combining all of the SSS correlation sequences; and
detecting SSS IDs according to a combination result.
However, because the received SSSs are not equalized, the non-coherent SSS detection method is of poor performance in a fading channel environment.